spark plug change =large mpg increase

[AVIDMOTION]

I had a set of XP5245 Autolite Xtreme Performance Spark Plugs gapped @ .040 , they are irridiums and should last 100,00 miles like the stock plugs. I got about 40,000 out of them. Though they seem to run fine, there was a slight miss at idle and no matter what I tried my MPG has been down. I pulled a plug and though they were nearly perfect tan, perhaps a little too light tan, but the top electrode -the "pad" was nearly gone or gone on plugs. The gap was avg .048 the largest being .052. Big difference from .040. I installed TR5 NGK's at .040. Idles perfect and a large immediate MPG increase! Went from 14-17 city and 19-21 highway(17.8 combined) to 18.7 city/26-31 highway/19.7 combined. All for 45 minutes work. I will change these every Spring or around 10,000 miles.

[GRRRR8]

Autolites have never been known for exceptional fuel economy. I think the TR5 is a little bit hotter plug as well. It may cross over to a TR5, but the true heat range is actually hotter. Which for your application is fine.

More $$$ for mods with the fuel savings! :)

[Executor999]

Do you recommend NGK Iridium IX TR-5IX or NGK V-Power TR-5?

[GRRRR8]

My guess is you are probably going to fall into the TR6 class Dan.

[Executor999]

Really? They say those are one step colder for forced induction/nitrous.

[GRRRR8]

In most applications 100HP over stock you drop 1 heat range.

[Executor999]

I see the TR6's also have two choices: Iridium and V-Power. :\

[GRRRR8]

Iridium is going to be a longer lasting more expensive plug. The V-Power is what most use as they are inexpensive and allow you to change/inspect plugs at a much shorter interval. I would say in a daily driver a Should be inspected at about 10k and a Iridium at about 20k. I don't like iridium in N20 applications or boost for that matter.

[barr1340]

Looking at my mods list ( add in a Maggie too). What would be a good replacement plug?


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[GRRRR8]

TR6 should be fine. Boost, compression, ignition timing all play a factor in what heat range plug you use.

If you have a stock G8 with headers, CAI and a tune that is adding close to 10 degrees of timing you would drop a heat range.

With your application cam, heads, headers, boost that would automatically be 1 heat range colder.

[barr1340]

Thank you


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[AVIDMOTION]

I took back my TR6 and replaced with close to stock-the TR5. I am done with Iridiums. Stock ones lasted 30,000, the extreme autolites lasted 35,000 but should have been replaced when I saw the big MPG drop about 5,000 miles ago. Literally it took 45 minutes beginning to end to replace the plugs, so every Spring I will just get new ones. Iridiums can last up to 100,000 miles, that being said, their true useful life is less then 30,000, by that time they lost 30 -50 % of their oomph. The copper gives its all for 10,000 miles, then they are junk too, but alot cheaper to replace. You can really feel a SOTP difference, more responsive, no bog, full midrange power right up to redline, and added MPG. Look I just sold myself!

[G8-4-Speed]

I had a set of XP5245 Autolite Xtreme Performance Spark Plugs gapped @ .040 , they are irridiums and should last 100,00 miles like the stock plugs. I got about 40,000 out of them. Though they seem to run fine, there was a slight miss at idle and no matter what I tried my MPG has been down. I pulled a plug and though they were nearly perfect tan, perhaps a little too light tan, but the top electrode -the "pad" was nearly gone or gone on plugs. The gap was avg .048 the largest being .052. Big difference from .040. I installed TR5 NGK's at .040. Idles perfect and a large immediate MPG increase! Went from 14-17 city and 19-21 highway(17.8 combined) to 18.7 city/26-31 highway/19.7 combined. All for 45 minutes work. I will change these every Spring or around 10,000 miles.

Computer control vehicles use resister style plugs to keep from getting voltage feedback on the ground side of the circuits. With all data being voltage based, you can shift O2's with a plug change. You should see my O2 scans when I run 3933 Autolite copper race plugs, it looks like someone stuck a vibrater on my O2's..With that said, if voltage bleeds to the ground side, it can offset O2's to read leaner and add fuel which will hurt gas mileage(were talking mV, nothing that will you will feel or shock you) . Thats the biggest problem with plugs. There is no magic, if it sparks, the fuel lights. The problem is in manufacturing and the resistance of the plug. I don't have an answer for the magic number, just know if you see interference, its going to have an effect.

[AVIDMOTION]

All my plugs have been resistor type plugs. All my cars have always done well with NGK plugs.

[SpeedRacerX]

OK, I am now confused.

I went to Pep Boys and they had the Iridiums (no), the platinum NGK TR5-BP, v-power something, and copper resistor NGK TR5 (with no designation after it). I think the copper TR5s were like $2.29 each. I did not see any TR5 with a designation of "NFL" after it.

avidmotion, did you just get the basic NGK TR5 for $2.29 each or did it say anything else??

Thx.

[I12XLR8]

Subscribed. I've got around 38000 miles on mine and was wondering when I should change the plugs...I guess I would go with the TR6 as I have LTH, 93 octane tune, and intake that GRRRR8 mentioned :huh:

[hayabusa160]

order them online at advanceautoparts. go on retailmenot.com and input coupon codes. click pick up in store.= profit

[AVIDMOTION]

they were NGK TR-5 resistor copper plugs. I had to order them and pick up next day. The TR6 was in stock, I had bought them but took them back to get the stock heat range since my other plugs ran perfect but were just wore out(Iridiums)

[SpeedRacerX]

they were NGK TR-5 resistor copper plugs. I had to order them and pick up next day. The TR6 was in stock, I had bought them but took them back to get the stock heat range since my other plugs ran perfect but were just wore out(Iridiums)

So we have similar mods. So TR5 & not TR6, right?


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[AVIDMOTION]

Yes NGK TR5- these are stock heat range and pre-gapped with the correct gap of @.040.
The NGK TR6 are one heat range colder are also pre-gapped. When I pulled my plugs they were running perfect, the color was perfect, just the plug was wore out, especially the "pad" at the top was nearly erroded away. So I stayed with the stock heat range. And now my car is running the best ever(New tune from Vector hit the nail on the head this time!)
After plug change an immediate gain in MPG, no more miss at idle, no surges, much quieter too, immediately responsive and I am sure some power in there too!

[Monty]

I had a shake at idle seemed almost like a miss. I installed NGK Iridium TR5 IX and the shake is gone. The original plugs I took out looked fine and they were still gapped at .040. It's been 5 days now and the car is running a lot better. That's at 24,000 miles.

[hayabusa160]

just swapped mine today. the back one was actually easier then the front one for me on the passenger side lol but i have small hands.

i also regapped the plugs. some were a tad tighter then .040

i didnt get to drive the car yet its late ill do it tomorrow i also pulled the neg on the battery to reset the ecu. the car had a slight hesitation and shakey idle i hope it will fix it.

[BLKG8]

I thought on changing out the plugs also but turns out i dont need to...... take a look at one of them...they have a little over 25k on them.
http://img.tapatalk.com/d03656b5-08b3-f687.jpg
http://img.tapatalk.com/d03656b5-08d5-5688.jpg

[MongosG8]

Was thinking going this route. Might take one out to see what it looks like tomorrow.
I'm seeing shitty gas mileage and some sputtering and I only have 13650 miles on my car. My G8 sits a lot and never really gets taken out at WOT too often to blow the shit that builds up in it. Just frustrated when your seeing 16-18 mpg HWY! That sucks!

[AVIDMOTION]

16-18 highway! Holy crap, thats terrible. Also that plug(BLKG8)looks like its running good, the pad at the top of mine was all but gone on most of mine.

[SpeedRacerX]

Changed my plugs today. Had 53000 on them.
Bought TR5's for $2.29 each.

Immediate improvement in idle, smoothness and response, etc.

Very happy.

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[texn884]

I got new plugs with my new engine so I sould be good for a while.

Any special tools needed for a rookie mechanic if you could call me that, lol.

16-18 HWY mileage SUCKS 25-30 ROCKS

[86cutlass350]

i put tr6's in my gf g8 gt and it lost et and lost mpg's.
im gonna put the stock plugs back in

[Posidon42]

So are the tr6's a good option for a fi engine? I have a cam/maggie and want to change out the plugs.

[carey]

I am at 64k miles now and pretty sure they have never been changed by the last owner. I am basically stock, just tune and exhaust so what plugs would you recommend for my DD that will give best benefits?

[gman08]

TR-5's or TR-55s. As for Posidon yes TR-6s are for FI/nitrous applications.

[AVIDMOTION]

Near stock or slightly more do the TR-5's. Got a supercharger, or cam etc, big mods, go with the colder TR-6. Let us know what you do and how it works out.

[GT Drew]

TR-55 are the same heat range as TR-5, but the 55's have a .060 gap. I run the 55's in my Regal.

[XXFire]

Ok, I guess some NGK TR6's when I get back from vacation...
50k on my GXP.
go with the TR6 since I have CAI,headers,cat back and tune right?

[TheWhiteKnight]

Sorry to revive an old thread, but I've got nearly 100,000 miles on my car and have never changed the plugs/wires. The only "mod" I have is a Cortex stock tune. It's my understanding (and I could be wrong, it's happened a time or two) that I should go with the NGK T-5's for plugs, correct? Anyone know where I can get these for less then $7.00 each (what both Amazon.com & Advance Auto Parts list them at)?

Thanks for all the help!

[SRG963]

Sorry to revive an old thread, but I've got nearly 100,000 miles on my car and have never changed the plugs/wires. The only "mod" I have is a Cortex stock tune. It's my understanding (and I could be wrong, it's happened a time or two) that I should go with the NGK T-5's for plugs, correct? Anyone know where I can get these for less then $7.00 each (what both Amazon.com & Advance Auto Parts list them at)?

Thanks for all the help!

I used ACDELCO 41104 from RockAuto

[WickedMom]

I have a set of low resistance 8mm wires and plugs for $149. I can see if I can get you that part number as opposed to the zr1 plug....

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[EcoBrick Bob]

I have a set of low resistance 8mm wires and plugs for $149. I can see if I can get you that part number as opposed to the zr1 plug....

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Which plugs? TR-6? If so I am interested. Going in an 09' with cam, stall, headers, ported heads etc. Vehicle only has 24K.

[WickedMom]

No, more so the expensive oem plugs. The TR6 plugs are super cheap local to anyone... unless I'm looking at the wrong ones.

PS. Why you no reply to my FF.net pm?

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[TheWhiteKnight]

I have a set of low resistance 8mm wires and plugs for $149. I can see if I can get you that part number as opposed to the zr1 plug....

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Interested! I'm assuming you are talking about these here http://www.superchargersonline.com/index.php?main_page=product_info&cPath=510_1101&products_id=7667?

Would I order this setup for a near stock G8 GT (as mentioned earlier in thread only have a tune with a Cortex, may add a Roto Fab at some point this year though), or would I need a different set of wires?

[WickedMom]

Yup! Ill find out on monday about the plugs. You wouldn't want ZR1 plugs in a NA car. The wires would be fine though :)

[TheWhiteKnight]

Yup! Ill find out on monday about the plugs. You wouldn't want ZR1 plugs in a NA car. The wires would be fine though :)

SRG said earlier he used the AC Delco 41104 plugs. Aren't those pretty much the stock plug, gapped @ .040"? All of this has me so confused :facepalm2:

Thanks for the help Wicked!

[LDM]

SRG said earlier he used the AC Delco 41104 plugs. Aren't those pretty much the stock plug, gapped @ .040"? All of this has me so confused :facepalm2:

Thanks for the help Wicked!

41-104s (also known as PN 12571165) are the ZR1 plugs, which is what I used when I added a supercharger.

http://i843.photobucket.com/albums/zz352/lenmartin23/G8/DSC_4961.jpg

[SRG963]

SRG said earlier he used the AC Delco 41104 plugs. Aren't those pretty much the stock plug, gapped @ .040"


That is my understanding. I was told there are no issues using the 41-104 with a NA engine.


These are the AC Delco Iridium spark plugs that come standard on the new C6 Corvette ZR1 and Z06.

I also got a $16 mail-in rebate check ;)

[WickedMom]

This whole spark plug crap is new to me. :-)

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[TheWhiteKnight]

This whole spark plug crap is new to me. :-)

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Me too.

What is the OE brand/model that comes with the car?

[EcoBrick Bob]

The stock G8 GT would use the Delco 41-110 iridium plug which is similar in heat range to the NGK TR-5IX or TR-5.

[TheWhiteKnight]

The stock G8 GT would use the Delco 41-110 iridium plug which is similar in heat range to the NGK TR-5IX or TR-5.

Thanks for the clarification Eco, greatly appreciated!

Assuming this kit, http://www.superchargersonline.com/i...oducts_id=7667?, is one of the best ways to go then, both cost and performance wise?

[LDM]

You said your only mods are a Cortex tune, right? Why not go with the stock 41-110s? The only GM engines that use the 41-104s are the LS9, LS7, and LSA. So unless you're putting out at least 500 hp at the crank, the heat range of the stock plugs would probably be best suited for you. If Jessika can't swap the 41-110s for the 41-104s in that package, you could always get them from Greg@Pace: http://paceperformance.com/i-5925537-41-110-spark-plug.html The list price is pretty cheap and if you PM him you could probably get them even cheaper.

Some food for thought on heat ranges:


http://www.youtube.com/watch?v=LbR75wq9nmM

Too cold of a plug and you risk excessive fouling.

[TheWhiteKnight]

You said your only mods are a Cortex tune, right? Why not go with the stock 41-110s? The only GM engines that use the 41-104s are the LS9, LS7, and LSA. So unless you're putting out at least 500 hp at the crank, the heat range of the stock plugs would probably be best suited for you. If Jessika can't swap the 41-110s for the 41-104s in that package, you could always get them from Greg@Pace: http://paceperformance.com/i-5925537-41-110-spark-plug.html The list price is pretty cheap and if you PM him you could probably get them even cheaper.

Too cold of a plug and you risk excessive fouling.

Thanks LDM. The only mod I have is the Cortex tune, correct. The only additional mod I may add later this year is a Roto-Fab. I'm fine with going with stocker plugs, just wasn't sure of the part number, and very confused with how plugs work in the first place. I didn't even think of checking Pace, or messaging Greg.

Again, thanks for everyone's help, greatly, greatly appreciated!

[It's A G8!]

So what would be the part number for the NGK TR6.

[768MPH]

http://ngksparkplugs.com/part_finder/car_truck_suv/results.asp

Google :huh:

[johnbell2]

I'm 140 hp over stock and use the AC Delco 41-110. They work just fine. I used to run NGK TR6... mistake, my mileage & power are better with the iridium plugs.

[cstmg8]

So, it seems as though there is a little disagreement on when to go with the TR 6.
Headers, full two and a half inch exhaust, intake, and 93 tune. Tr5 or tr6?

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[MongosG8]

Funny I see this old thread come back to life.

Just last week I noticed some sputtering..hesitation when I left a green light. I thought it was this crappy ethanol gas mix in CT.

Does anyone think it can be the plugs? My G8 sits a lot..its more of a garage queen than a daily driver.

[djchubbs]

So with a CAI and a super chips tune what NGK would be recommended I am at 50k and would prob change them.

[768MPH]

So with a CAI and a super chips tune what NGK would be recommended I am at 50k and would prob change them.

NGK TR-5ix or TR-5s